1. Field of the Invention
The subject invention relates to mobile cellular networks, and more particularly, to a handover scheme based upon channel quality measurements.
2. Description of the Related Art
A mobile cellular network is a radio system which provides radio communication for mobile terminals over a large geographical area. Cellular networks generally consist of a plurality of base stations arranged in a systematic pattern throughout a geographical area to define a plurality of adjoining cells of between 2 and 20 kilometers in radius.
Typically, a mobile terminal in a particular cell communicates through a radio channel provided by the base station of that cell. When a mobile terminal is traveling between adjacent cells of a network, a handover must be performed whereby the mobile terminal terminates communication with the base station of one cell and initiates communication with the base station of another cell.
Techniques for effecting handovers in cellular networks are known in the art. A common technique involves the continuous measurement of the strength of voice signals. Usually, the RF (radio frequency) signal strength of mobile communications within a particular cellular network are monitored by a system controller. When the RF signal strength of a particular mobile communication falls below an acceptable level, the system controller will initiate a handover from one base station to another. Such a handover method is effective in noise-limited cellular systems. However, in interference-limited systems wherein noise is prevalent, received signal strength measurements can be distorted by interference from adjacent channels or co-channel radio signals. It would be beneficial therefore, to provide a handover procedure that is unaffected by noise and/or channel interference.